Gov. Tom Corbett signed legislation in February allowing the use of audio recording devices on school buses, and many districts are taking advantage of the law. The recordings can be used for "disciplinary and security purposes," the bill states. Video surveillance already was permitted.

Almost a decade after bus company Laidlaw Transit was found to be collecting audio recordings of students from West Mifflin Area School District without their consent, the district now has authorized audio surveillance on buses. Pittsburgh, McKeesport Area, Gateway and Seneca Valley also have adopted policies allowing the taping.

A "high volume of incidents" on buses prompted a need for increased security and monitoring, said Dan Castagna, West Mifflin Area superintendent, who hopes the recordings will be a "deterrent."

"You have lots of students crammed into a small space, so it seems like no matter what we do, we see busing issues arise," Castagna said. "A lot of times you get a lot of 'he said, she said' and have a hard time getting the whole story. Now we can see what you're doing and hear what you're saying."

Woodland Hills School District was "ahead of the pack," using audio recordings on most of its buses since 2009 based on a letter from the district attorney, said Superintendent Alan Johnson.

"There are no teachers and principals on the bus, just the driver," said Johnson. "Sometimes they're working with 30 or more students, so that can become very problematic. It's hard to discern how incidents started and who was saying what without the audio recording."

The issue was brought to the forefront in 2006 after Laidlaw Transit, now part of Cincinnati-based First Transit, was found to be collecting audio recordings of students without their consent.

State police, while investigating a driver's complaints that he was forced to operate overcrowded buses, discovered audio recording equipment on vehicles used to transport students in the McKeesport Area and West Mifflin Area school districts.

Stephen A. Zappala Jr., Allegheny County district attorney, chose not to prosecute the bus company, citing no intent to violate the state's Wiretapping and Electronic Surveillance Control Act, which prohibits taping conversations without a party's consent.

Instead, he distributed a letter to area school districts stating the use of audio equipment on school buses would not be considered a "criminal matter" within the county if district school boards adopt a policy allowing audio recording for "disciplinary purposes," parents and students are notified in advance of the policy in a letter and "visible notices" are posted on the buses informing riders that video and audio recordings are taking place.

Eight years after Zappala's letter circulated to school districts in Allegheny County, the Legislature approved an amendment to Senate Bill 57 that exempts school buses from the state's wiretapping laws.

"We viewed it as a protection bill for the school bus drivers who are driving a machine weighing thousands of pounds, trying to focus on the road while carrying dozens of kids with their backs to them," said sponsor Sen. Richard Alloway, R-Adams, "It protects the drivers and also the kids."

Steve Robinson, spokesman for the Pennsylvania School Boards Association, said the amendment prompted questions from school districts and interest about how to adopt audio taping into board policies. Besides notifying parents and students of the change, the policy must include a provision that audio is turned off if the bus is not being used for school purposes, he said.

David Sunstein, president of Pennsylvania Coach Lines - which serves at least a dozen area school districts - said the April stabbings at Franklin Regional High School changed the conversation surrounding school and student safety.

Sunstein said there have been instances in which other students and bus drivers said they were verbally threatened but disciplinary actions were limited without proof of the incidents.

"If a kid says, 'I'm going to bring a gun tomorrow,' now you have it on tape," Sunstein said. Since the Franklin Regional incident, "you have to take every threat seriously. It's very beneficial having that on tape so we can have instances to play back."

Some civil rights proponents, though, argue further sacrificing privacy is too great a cost.

Andy Hoover, legislative director of the American Civil Liberties Union of Pennsylvania, said the legislation has "severely diminished" students' right to privacy.

"We're teaching our kids to be accepting of the surveillance state, that they're going to be watched at all times," Hoover said. "They discuss sexuality, their home situation, their academic situation - and administrators could be picking up on those conversations if the technology is strong enough. I would hope that administrators are thoughtful enough to address challenging situations without having to put a microphone on every student in the building."